john5099

My 2015 GL450 has less than 8500 miles. I keep getting warning of low coolant , but looking at the reservoir, it doesn't seem to be low. I read in other places that low wiper fluid can cause this error as well. My wiper fluids were low, so I put in about a half a gallon and it made the warning go away for about 5 days. I haven't used any wiper fluids during this time, now the warning is back on. Anybody else run into this?

Thanks

cadetdrivr

Yes, this is not that uncommon and there are numerous reports on this forum. The system has a VERY sensitive low level sensor and that sensor is not necessarily calibrated with the visual indicator.

It seems like the factory ships the trucks near the minimum fill level and then it takes a few thousand miles for the coolant to find its level within the system despite the fact the visual indicator remains within the normal range.

I bet you can have your dealer add a tiny amount and it will be fixed and you'll never have to worry about it again.

Elric99

Had this on my 450 recently. They added a tiny amount and it fixed it.

Mike450

Yes, 8800 miles myself and the cold weather seems to have brought it on. Appears every morning but seems to be a non issue once the motor is warm.

43221B

I'm on my second X166. Both have had this issue. Both have used coolant and you will need to add some every 5000 to 10000 miles. You can smell the coolant when the engine is hot and you stand beside the left front wheel which is near the reservoir. It's annoying but I purchased distilled water, MB coolant, and a pyrex measuring cup to periodically fill. As long as it only uses the coolant slowly, I'll add it myself. I don't want anyone tearing things apart to fix this. It could be as simple as a bad cap on the reservoir. Many of us have complained about this.

43221B

When the coolant is hot, it raises the level in the reservoir. That's why the low coolant warning goes off with a hot engine. You need to add about a cup of coolant/distilled water and you'll be good for another 5,000-10,000 miles.

SFML320

Ditto - same issue with our 2007 GL and now same with 2013

john5099

I would think that only reason you would need to refill it on some interval is if there is a leak. Similar to Freon in AC units, both are closed system no? If you start dropping either, wouldn't it indicate a leak?

Oh well, I have the 10K service coming up so I will ask them the same.

luv2sleep

Ours came on also at less than 10,000 miles. Easy DIY. While you are at it, I'd also check the turbo coolant (exact same type of coolant-red in color) located under the plastic engine cover. Mine was a little low also but not too bad. They must "under fill" the coolants when they ship these vehicles. Kind of a nuisance if you ask me.

dryla

I have a 2014 GL450. Since my dealer is 100 miles away, I looked to Amazon for coolant to have on hand - just in case a bit is needed to keep the levels topped off. Mine, like yours, is red(or pink) in color. All that I saw on Amazon was blue in color yet they have the MB 325.0 corrosion spec. Are the blue and the red(or pink) compatible if just a small amount would need to be added and mixed? If not, is there any source for the red other than the dealership?

luv2sleep

I know I'll catch flak for saying this from the **** crowd but glycol is glycol. Just go to any auto parts store and get a jug of antifreeze. If it makes you feel better, get the one that says, "any color any make" or something to that effect. If you live in some God forsaken northern state like North Dakota with inclement weather, make sure that the stuff you're buying can withstand -xx degrees. If you are uncomfortable with it, then as someone else have said, fill it with some distilled water and it'll do the trick.

byroncheung

i had the turbo coolant pipe issue couple of years ago and an indy shop replaced the pipe.

lately i have noticed a slow leak (last time when the coolant pipe went bad the leak was quicker, i'd refill and next day it would be low again), the low indicator would come on every a few months and i have been topping it up. lately i have noticed small puddle (not a lot maybe a few drops) on my garage floor semi-regularly (seems like if i leave the car there long enough i will see some), under the the driver side front pumper. looking under the hood i can see some liquid pooled on the tray around there. took it to another indy but the guy said he pressure tested it and can't find the leak?

johncspierce

I keep getting the same message on my 2015 GL550. I add coolant/water, but also notice an additional expansion/recovery tank that is engine mounted in the center under the center motor cover. Do you add coolant to this as well? The manual is silent on this.

byroncheung

no I only add to the main coolant tank on the side of the engine bay, that would make the error message go away. At the end, for my car, the leak get gradually more severe to a point I have to add every week, they did find a crack in the radiator, changing the radiator fixed it.

silvergl

you could just replace the bottle/ sensor, it only takes a few minutes. you need the inverted torx driver however.